Stearns v. United States was a Supreme Court case that addressed the issue of whether a federal court had the authority to issue a writ of habeas corpus to a prisoner held in a military prison. The case arose when a prisoner, William Stearns, was held in a military prison in Washington, D.C. after being convicted of a crime in a military court. Stearns sought a writ of habeas corpus from a federal court, arguing that he was being held in violation of the Constitution. The Supreme Court held that the federal court did not have the authority to issue a writ of habeas corpus to a prisoner held in a military prison. The Court reasoned that the writ of habeas corpus was a civil remedy, and that the military was a separate branch of government with its own laws and procedures. Therefore, the Court held that the federal court did not have the authority to interfere with the military's proceedings. The Court's decision in Stearns v. United States established the principle that the federal courts do not have the authority to issue writs of habeas corpus to prisoners held in military prisons. This principle has been applied in subsequent cases, and remains an important part of the law today.

In Stearns v. United States, the Supreme Court was asked to decide whether a federal court had jurisdiction over a case involving an alleged violation of the Fugitive Slave Act. The majority opinion held that it did not have such jurisdiction and dismissed the case. However, Justice Swayne dissented from this decision, arguing that Congress had intended for federal courts to have exclusive jurisdiction in cases involving violations of this act and thus they should be allowed to hear them. He further argued that if state courts were given authority over these matters then there would be no uniformity or consistency in how fugitive slaves were treated across different states which could lead to injustice being done against those seeking protection under the law. As such he concluded that allowing only federal courts to adjudicate these cases was necessary for justice and fairness in their resolution.